Re: [ACPI] PATCH-ACPI based CPU hotplug[2/6]-ACPI Eject interface support

Dmitry Torokhov
2004-09-22T03:10:07Z

On Tuesday 21 September 2004 04:51 pm, Keshavamurthy Anil S wrote:
> On Tue, Sep 21, 2004 at 12:51:36AM -0500, Dmitry Torokhov wrote:
> > On Monday 20 September 2004 08:38 pm, Keshavamurthy Anil S wrote:
> > > Currently I am handling both the surprise removal and the eject request in the same
> > > way, i,e send the notification to the userland and the usermode agent scripts
> > > is responsible for offlining of all the devices and then echoing onto eject file.
> > >
> >
> > I actually think that on the highest level we should treat controlled and
> > surprise ejects differently. With controlled ejects the system (kernel +
> > userspace) can abort the sequence if something goes wrong while with surprise
> > eject the device is physically gone. Even if driver refuses to detach or we
> > have partition still mounted or something else if physical device is gone we
> > don't have any choice except for trimming the tree and doing whatever we need
> > to do.
>
> I agree, but when dealing with devices like CPU and Memory, not sure how the
> rest of the Operating System handles surprise removal. For now I will go ahead and
> add a PRINTK saying that BUS_CHECK(surprise removal request) was received in the
> ACPI Processor and in the container driver, and when we hit that printk on a
> real hardware, I believe it would be the right time then to see how the OS behaves
> and do the right code then. For Now I will just go ahead and add a PRINTK.
>

Heh, I really don't expect the kernel to survive if somebody just yanks out a
CPU without a warning, especially if the CPU is the last one :) I hand in mind
devices like my port replicator that only has an additional network card and
could survive surprise removal.

> Let me know if this step by step approach is okay to you.

It sure is, we can always adjust the process down the road.

Thank you for your work!

--
Dmitry